Studies of the cell physiology and pathophysiology of various pure lung cell types in tissue culture systems will be pursued. These studies involve both normal lung cells and the effects of hypoxia, hyperoxia, redox environmental pollutants and osmotic alterations on these cells. Lung cell types studies will include Type II pneumocytes, alveolar macrophages, lung fibroblasts, pulmonary artery endothelium and A549 lung tumor cells. The areas of study include: 1. Studies of the mechanism(s) by which molecular O2 modifies activity of various enzymes. 2. Studies of the mechanism by which high concentrations of molecular O2 increase cAMP content and the relation of this to inhibited replication. 3. Validation or rejection of a theory that oxidant injury is related to cAMP overload. 4. Bioenergetics of isolated endothelial cells and A54 lung tumor cells and the effects of hypoxia and hyperoxia. 5. Effects of osmolality on lung cell and mitochondrial energetics.